1. Field of the Invention
The invention relates in general, to firearms and, more particularly, to firearm receivers which facilitate directly connecting both the barrel and the handguard directly to the receiver of the host firearm, each independent of the other.
2. Description of the Related Art
The use of autoloading rifles is prevalent with military, police and civilian shooters. Of the various autoloading rifle designs, few can compare with the popularity of the M16 family of firearms and its derivatives. The M16 family of firearms includes, but is not limited to, the AR15, M4, AR10, SR25 and piston operated designs such as LWRC International's M6 series of rifles. In general, the M16 family of firearms includes a lower receiver having a stock coupled to the rear end which is connected to an upper receiver having a barrel coupled to the front end. The chamber end of the barrel is received by a portion of the upper receiver and threadedly secured in place by a barrel nut.
Handguards are secured about the barrel to provide a surface by which the user may support the forward end of the firearm, protect the user's hand during use, and provide a mounting platform for optics, lights, lasers and other devices which may become useful. Conventional handguards found on prior art M16 type rifles are not ideal for mounting secondary devices such as lights, lasers and optics. To more easily facilitate the mounting of such devices and for other advantages, handguards which incorporate a series of MIL-STD-1913 rails, or Picatinny rails, about their exterior were developed. An example of this type of handguard is the rail adaptor system (RAS) found in U.S. Pat. No. 5,826,363. The RAS consists of an aluminum tube that replaces the conventional handguard. The tube has a series of MIL-STD-1913 rails at the 3, 6, 9, 12 o'clock positions running along the longitudinal axis of the bore. MIL-STD-1913 rails allow for the easy installation and use of various accessories which enhance the functionality of the host firearm. The aluminum tube at the heart of the RAS is secured to the prior art barrel nut and at a point on the barrel itself. By contacting the barrel, the weight of accessories mounted to the handguards can affect the zero of the host firearm.
Subsequently, a variety of designs were developed. Some early designs rely on being supported by the legacy barrel nut of the M16 family of firearms. Other designs have been developed which rely on a proprietary barrel nuts that are used to secure the handguard and barrel to the receiver, effectively “free floating” the barrel. Free floating the barrel implies that the handguard is not in direct contact with the barrel of the associated firearm. By eliminating direct contact between the handguard and the barrel, the host firearms accuracy and precision are generally improved. Further, the zero established with the host firearm will not be affected by the mounting of optics, lasers, lights or other accessories to the handguard. However, the handguard used with these free floating designs can still flex. The flexing of the handguard occurs at the junction where the handguard is attached to the barrel nut which is in direct contact with the barrel. If sufficient weight or torque is applied to the handguard, such as through the use of a vertical grip, the zero of the weapon can be compromised. This flexing of a free floating handguard can also lead to premature wear of the host firearm's bolt.
Another design path which has been taken is manufacturing the upper receiver with an integral railed handguard. An example of these so called “monolithic” upper receivers is found in U.S. Publ. No. 2011/0005384, which includes a handguard that is integral with the receiver so that the handguard assists in retaining the barrel. This configuration, and those like it, have several disadvantages. Should the handguard become damaged in anyway, the entire receiver with integral handguard must be replaced. This places a substantial financial burden upon the user. Further, the barrel is retained within the receiver extension of the receiver by securing the barrel to the handguard. Through the use of steel screws, the forward movement of the barrel is resisted. Unfortunately, the steel screws used to secure the barrel in place can potentially become over-torqued. Over-torquing the screws can cause the heli-coil threads, or their equivalent, used for retaining the screws to bind up in the receiver, making future repair difficult and expensive. Alternatively, should the threaded inserts become damaged while the screws are being secured in place, such damage could prevent the barrel from being properly secured within the upper receiver thereby rendering the host firearm inoperable.
Therefore a need exists for a receiver assembly in which the barrel and the handguard are each directly secured to the upper receiver, independently of each other.